Such a sieve screen is known from the Applicant's German utility model DE 202006001257 U1. This prior known piece of equipment provides a good separating capability and high capacity with respect to other sieve screens available in the marketplace. Also, the screen obstruction problems are avoided even with wet materials and, if necessary, even small fraction sizes can be screened. However, this prior known sieve screen involves a drawback that each sieve screen bucket is only applicable to one fraction size. This drawback is also present in the sieve screen bucket disclosed in the Applicant's patent application FI 20135247.